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Old 25th Sep 2006, 08:39
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The answer to all our secrets

Went to Birmingham on Saturday PM and watched this Monarch A320 take off and noticed that the undercarriage was staying down for an unusually long time. Then heard the pilot inform the tower not to worry as they were leaving it down on purpose and off they went with it still down.

Anyone suggest a reason?
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Old 25th Sep 2006, 08:56
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I have heard of this done before when the guys took off with high brake temps. If you pull the gear up then the temp falls much slower. I whon't comment on whether they should have taken off with high temps in the first place regarding perf and sop's. I have sat agast once though with my training Captain listening with interest when an F/O explained how they took off with 2 temps at 350 and just 'left the gear down to cool them a bit'. Find this hard to believe with Monarch though, very high standard of SOP's etc. They may have had an ecam indication, windshear warning etc wher they thought better just to climb up a bit before sorting things. When you raise the gear the doors open and in fact cause an increase in drag, if you have something happening windshear for instance then that's the last thing you want to do so you leave it be. One would have thought though they would have given some indication to ATC, but when you are climbing out of Birmingham and maybe you have a slight problem your RT could be effected.
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Old 25th Sep 2006, 14:47
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Nothing too unusual and I've seen it lots of times. I told an Air France Airbus he had his gear down as he climbed away. "Affirm; we use it for take-off" was the response!
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Old 27th Sep 2006, 14:42
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One would have thought though they would have given some indication to ATC,
I can rem some years ago a 747 Classic getting a call from the Tower after take-off, querying why it's U/C was left down? ..... just cooling the brakes came the reply .....
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Old 27th Sep 2006, 14:58
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Can I ask why the brakes would get hot on take off?
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Old 27th Sep 2006, 17:37
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Most likely a brake problem (usally a tachometer) that means that the brake has been disconnected. The brakes are applied automatically during the retraction sequence to stop them rotating, if the brake is disconnected then you have to leave the gear down for 2 minutes after take-off to allow it to stop spinning. Quite why it's considered such a problem to have them rotating in the wheel well I don't know. Take-off and landing performance are both reduced via a table with one brake inop, and obviously if you have an engine failure you retract it anyway.
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Old 27th Sep 2006, 17:54
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you leave the gear down when the brake is deactivated till the wheel stops (2 mins) as the wheel acts as a jyro and will put wear on the undercarriage because of the strain of moving the wheel through 90 degreases and slows the retraction on that side by up to 90secs (a300)
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Old 2nd Oct 2006, 10:40
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when landing you apply manual braking and the temps go up. If for some reason (usualy a bit heavy footed on them) the brake temps are high you need to cool them. Some aircraft have brake cooling fans that you switch on to help. But if you havent got these and you are on a short turn around or the pilot applies to much braking in the taxi to takeoff then you have high temps again. Most likely that the pilot flying could have been under line training and a bit to heavy on the feet but as you have read there could be a thousand reasons
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Old 2nd Oct 2006, 11:18
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I was the FO. Captain called 'GO' just before 100kts when we got a BRAKES HOT Amber ECAM warning on one brake - only 300ish degrees. We decided to leave the gear down to cool it off and the Captain made a great call to the tower so everyone knew what was going on. Cooled it down, got them up, and off to wherever we were going. Probably a quick turnaround and the long taxi down to 15 put some heat into the brakes.
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Old 2nd Oct 2006, 12:28
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Fatboy slim

I have it on video, if you want a small AVI of yourself let me know.
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Old 1st Nov 2006, 21:31
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The answer to all our secrets

When Commercial style Aircraft steer during taxiing, what parts of the actual Aircraft are used to carry it out?
I always notice the actual nosewheel turning, but was wondering whether using left or right engine thrust and the rudder assists.
Also on a recent flight I was on (A320) I noticed the Aileron being raised on a wing (depending on the direction turned).
 
Old 1st Nov 2006, 21:49
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Nosewheel normally via a steering wheel in the cockpit.

Use of aileron while turning on the ground is unusual - mind you, an Airbus............................
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Old 1st Nov 2006, 22:37
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In A320 aileron movement will be when flight deck are doing the flight control checks. First PF then PNF (or Capt then FO depending on SOPs) does them so you will see them move twice.

Normally most of the steering is done by the nosewheel. Sometimes differential power can be used on tight turns but it can put more strain on the main landing gear.
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Old 2nd Nov 2006, 10:30
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what about differential braking like in a light a/c? Is this done in jets when taxiing around tight corners?
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Old 2nd Nov 2006, 13:13
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With the larger aircraft unless it is tight the nose wheel steering is anough for turning.

Where large aircraft need to turn on the runway to backtrack for a turn off yes the engine power does need to be used.

Light twins do not normally have sperate steering it is done through the nose wheel and braking and the engine help in the turn.

Aircraft from the commuter size seem to be the first aircraft to have a steering wheel or tiller (A Twin Otter has a tiller this is like a column change gear stick in a car up to turn right and down to turn left).

Sometimes controllers put pressure on pilots to do a tight 180 degree turn on the runway which does put a strain on the near undercarriage leg, an Aurigny Air Services ATR went into engineering with in the last week with a cracked undercarriage some tight turns may have caused or not helped this.

Our runway is 46 metres wide the turning circle i understand for a Boeing 757 is 45 metres so you have not got a lot of room either side, aircraft have gone farming before now by turning on the runway and going over the edge.

Not only the pilot being red faced but the controller could take some of the blame by better use of the taxiways or dumbell turning circles at the end of some runways thats my oppinion any way.
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Old 2nd Nov 2006, 13:47
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Try a Tiger Moth for fun.

No brakes, no steering other than power and rudder or a handler on each wing-tip.

Downhill and downwind, you need to be very careful.
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Old 3rd Nov 2006, 18:26
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Wink contrails

HELLO>>>FRIENDS¬!!!

What exactly are contrails?
What makes them occure?
Has ist anything to do with polution
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Old 3rd Nov 2006, 20:10
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all you ever wanted to know about Contrails ....

try this Google ....

http://www.google.ie/search?hl=en&q=...trails%3F&meta=
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Old 3rd Nov 2006, 20:14
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Contrails..... a "shorthand" for
Condensation Trails. The Hot Gases exiting a Jet Engine leave a "Vapour Trail" across the sky. It is merely the hot air [exhaust] meeting the cold air [atmosphere], and being visible. At different altitudes, the Con/Vapour trails are NOT visible due to atmospheric conditions...[temperature/pressure gradient..etc]. Converely, sometimes, due to the same "atmospheric conditions".....Con/vapour trails seem to last for eveeer ........
hope this helps
watp,iktch
thanx hobie

Last edited by chiglet; 3rd Nov 2006 at 20:16. Reason: hobie did a googly...
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Old 3rd Nov 2006, 20:28
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thanx hobie
your very welcome ....
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